I went on a 20 mile, two day backpacking trip on the Appalachian Trail. The forcast for the weekend was a 40% chance of rain. I am glad that I purchesed the Rain cover for my Oprey Auether 70 backpack, because it rained during the night, as well as most of the second day. However the raincover did a great job keeping my gear dry the entire time. Its light, and doesnt take up any room.